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A series of monomeric tetrahedral complexes of stoichiometry, [MX(HL)(Ph 3 P) 2 ] (In case of M = Cu, H 1 L, X = I, 1 ; Br, 2 ; Cl, 3 ; H 3 L, X = I, 4 ; Br, 5 ; Cl, 6 ; H 4 L, X = I, 7 ; Br, 8 ; Cl, 9 and in case of M = Ag, H 1 L, X = Cl, 13 ; Br, 14 ; H 2 L, X = Cl, 15 , Br 16 ; H 3 L, X = Cl, 17 , Br, 18 ) were synthesized by the reaction of copper (I) or silver (I) halides with indole-3-thiosemicarbazone (H 1 L) or 5-methoxy indole-3-thiosemicarbazone (H 2 L) or 5-methoxy indole- N 1 -methyl-3-thiosemicarbazone (H 3 L), whereas dimers of stoichiometry, [Cu 2 (μ-X) 2 (η 1 -S-H 2 L) 2 (Ph 3 P) 2 ] (X = I, 10 ; Br, 11 ; Cl, 12 ) were obtained by the reaction of copper (I) halides with indole- N 1 -methyl-3-thiosemicarbazone (HIntsc-N 1 -Me, H 2 L). The synthesized complexes were characterized using NMR ( 1 H and 13 C) and single crystal X-ray diffraction (H 2 L, 3 , 7 , 8 , 10 , 11 and 13 ) as well as elemental analysis. Anti- M. tuberculosis activity of ligands ( H 1 L - H 4 L ) and their metal complexes ( 1 – 18 ) were evaluated against M. tuberculosis H37RV strain ATCC 27294. It has been observed that there is unusual enhancement in anti TB activity of these ligands on complexation with copper (I) and silver (I). Molecular modelling studies in the active binding site are also giving complementary theoretical support for the experimental biological data acquired. [ABSTRACT FROM AUTHOR]

[Display omitted] • Presence of heterocyclic rings on aldehyde/ketone facilitates the formation of respective selenosemicarbazone. • Geometry of ligands is confirmed by 2D NMR. • Excellent anti-Tubercular activity shown by synthesized compounds (H1L , H3L , H5L , H6L). Reaction of cyclohexanoneselenosemicarbazone with aldehydes and ketones containing heterocyclic rings (2-oxindole, 6-cholro-2-oxindole, 3-methyl-2-oxindole, isatin, 1-methyl isatin, furfural, pyrrole-2-carboxldehyde) in ethanol yielded, respective, selenosemicarbazones {2-oxindoleselenosemicarbazone (2-HOxsesc, H1L), 6-chloro-2-oxindole selenosemicarbazone (6-ClHOxsesc, H2L), 3-methyl-2-oxindole selenosemicarbazone (3-MeHOxses, H3L), isatinselenosemicarbazone (HIstsesc, H4L), 1-methyl isatinselenosemicarbazone (1-MeHIstsesc, H5L), 2-thiopheneselenosemicarbazone (2-Hthiosesc, H6L), 2-furfuralselenosemicarbazone (2-Hfursesc, H7L) and 2-pyrrole selenosemicarbazone (2-Hpysesc, H8L)}. However the similar reaction with aldehyde containing single aromatic ring (3-chlorobenzaldehyde and 4-chlorobenzaldehyde) formed 1, 2-bis(3-chlorobenzylidiene) hydrazine (A) and 1, 2-bis(4-chlorobenzylidiene) hydrazine (B) rather than selenosemicarbazone. All the synthesized compounds were characterized using IR and NMR (1H, 13C) spectroscopy. Structure of A and B were confirmed by single crystal X-ray crystallography. The synthesized selenosemicarbazones were tested for their anti-tubercular activities and H1L , H3L , H5L and H6L are found to exhibit excellent anti-TB activity. The experimental data will give an opportunity to examine their anti-tubercular activities and identify the lead molecule. [ABSTRACT FROM AUTHOR]